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Review and Measurements of Purifi 1ET400A Amplifier

PierreV

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I have read many times in these forums that vinyls have a DR higher than their CD equivalent. Many times. It turns out that it is not true. What is the use of putting the link to dr.loudness.war in the first comment?

@Thomas savage

I suppose you will apply the same criteria to certain comments that are supposed to be funny and that are often used to discredit personally (in others threads), demonstrating with it the inability to argue properly.

Maybe they are the consequence of the carpet bombing?

I would suggest you create two threads

- Maty's listening impressions for the constant vinyl/CD DR comparisons.
- Maty's image collection for most of the pictures you post.

Some of your posts are interesting and on-topic, such as the ones where you got several manufacturers to provide information. But the rest, although possibly of interest to some, is just annoying, especially on a phone. The constant stream of large pictures, the creative highlighting, random DR values in every thread... My eyes are a bit sore, especially when I am only interested in the technical aspects of the Purifi amplifier and what the set of electronically competent board members think about them.

Please do note that I don't think either you or me are members of that electronically competent subset of board users... :)
 

Mtbf

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In summary this is one of the most lucid discussions of audio that I have read. The sense of mastery, humility, and passion is palpable to me in my reading of it.

I completely subscribe your description of this great interview, it gave me exactly the same feeling. So openhearted, the nuances, the hint of self-mockery, no self-indulgence whatsoever. And they truly listen, to keep verifying what they are doing and measuring, as they dit in the Hypex succes story.
Finally it is helping me to come to terms with the fact that I am auditioning two excellently measuring amplifiers and have a completely different subjective experience of them. I think I now know why one is going to be returned tomorrow.
I for one would be very interested in the results of your auditioning, and to hear from you which of the two amplifiers you finally returned (the NAD or the AHB2?), because I am stuck in about the same dilemma.
 

Robbert

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I have a question. I have both the hypex nc400 kit and neurochrome modulus-86. Both measuring very well. The nc400 has an unpleasant hardness in the sound the modulus doesnt have. I'm sure the quantity contributing to this hardness must be measurable. I just don't know what quantity it is. It is obvious enough when listening to music. My main interest here is, will this hardness be adressed in the purifi modules? And, is the origin of this hardness known (assuming this is a known and investigated phenomenon)?

Thanks!
Rob
 
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orangejello

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I have a question. I have both the hypex nc400 kit and neurochrome modulus-86. Both measuring very well. The nc400 has an unpleasant hardness in the sound the modulus doesnt have. I'm sure the quantity contributing to this hardness must be measurable. I just don't know what quantity it is. It is obvious enough when listening to music. My main interest here is, will this hardness be adressed in the purifi modules? And, is the origin of this hardness known (assuming this is a known and investigated phenomenon)

Thanks!
Rob
It may be the input module? I have not heard this problem with the NAD M22 v2 which has a different input module. I can listen for hours without irritation even when using the RME ADI-DAC 2 which is pretty ruthless.
 

orangejello

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I completely subscribe your description of this great interview, it gave me exactly the same feeling. So openhearted, the nuances, the hint of self-mockery, no self-indulgence whatsoever. And they truly listen, to keep verifying what they are doing and measuring, as they dit in the Hypex succes story.

I for one would be very interested in the results of your auditioning, and to hear from you which of the two amplifiers you finally returned (the NAD or the AHB2?), because I am stuck in about the same dilemma.
Sending you a private message. Subjective opinions are not allowed here - and no, I did not do a blind test. So if you want to regard my observations as worthless, that is fine.
 

Massimo

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Sending you a private message. Subjective opinions are not allowed here - and no, I did not do a blind test. So if you want to regard my observations as worthless, that is fine.

I would also appreciate your opinion on these two amps, subjective or otherwise.
 
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Xulonn

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Subjective opinions are not allowed here
That is absolutely not true - subjective opinions are very much allowed here, and everyone here states their "opinions" regularly.

What is "not allowed" is the ad nauseum repetition of myths and fallacies that have been dis-proven by rigorous, controlled testing and pointed out by other participants at this science-based forum.

And of course, the most egregious error one can make here at ASR is the stating as fact your untested opinions - especially information that has been repeatedly confirmed as being false or wrong. Such pronouncements by newbies here will at first lead to a polite and reasoned attempt to correct and educate. "Stating as fact" one's claims of clearly audible differences based on known flawed comparison and testing techniques exposes ignorance, and is often accompanied by a refusal to accept hard evidence refuting those claims. If that someone refuses to read the references provided, will not accept proven facts, wll not respond to questions, and refuses to at least attempt to do simple and valid blind testing, they should expect to be challenged seriously...and even excoriated if they continue to champion known myths and fallacies.

But why anyone would want to come to a science-based forum and try to use that forum as a platform to propagate myths and fallacies is quite mysterious.

So if you want to discuss subjective hard-core audiophile nonsense with someone here, please do indeed take it off-line - or to another forum. But spare us your untrue snide remarks.
 

March Audio

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The intermodulation effects of ultrasonic content were studied in this paper.
Thanks that is an interesting read and has saved me getting the microphones out to do this exact testing

Basically if you blast the speaker with high enough level ultasonic signals (well over 70dBSPL) that are still within its response range (24kHz+28kHz), some IMD can just be detected in the absence of any other in band music signals.

There is simply no musical content with ultrasonic signals at this level.

Using selected ultrasonic signals higher than 70 dBSPL, IMD could be measured in all three loudspeaker systems tested and it was just audible in the absence of any signals below 20 kHz. Care should therefore be exercised when designing experiments to determine hearing thresholds for combinations of high-frequency tones in the absence of correlated sounds below 20 kHz. For a large corpus of commercially available recordings, where the peak playback signal spectrum level above 23 kHz will be lower than 40 dBSPL, there is a very wide safety margin between any resulting IMD and the high masking level of the baseband music itself.

So clearly as the speaker response falls off with increasing frequency, the likely hood of any amplifier ultrasonic noise/distortion causing IM in speaker drivers is vanishingly small. Well, its just not a realistic proposition. It should be noted the test signals were all kept within the response range of the speakers.
 
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March Audio

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It was an interesting read. But was it skewed to suit the MQA narrative?
well... I dont think so, but I did bulk at the first statement
High-resolution recording and playback systems should accept signal components above 20 kHz and preferably reproduce above 40 kHz

On what basis? You cant hear it, and in theory at least, it has the potential to create in band IM problems.?!?!?!?!

It also seemed a totally pointless exercise to stimulate the speakers with such unrealistically high SPL ultrasonic signals that will never occur in any real recording.

The conclusion really is "nothing to see here".
 
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Tks

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Sending you a private message. Subjective opinions are not allowed here - and no, I did not do a blind test. So if you want to regard my observations as worthless, that is fine.

I don't understand why people always do this. Any disapproval of a single or few, equals somehow intolerance in totality from the whole? This detonating exit tactic is what modern day people who get 'offended' do. Not because they're actually offended, but because they want to *as implied* leave the conversation but with the last word, or to make it clear they concede no no points, nor admission of understanding of the replies to the statements made by the other person.

Subjective reviews are allowed here. What draws the ire of many is subjective reviews that bleed into subjective opinions on decades long established facts, but not supported by evidence to at least retort against these established facts. It's like saying "This amp is different for X reasons, and I hear it" because of such "Y principle in physics doesn't apply to me, regardless of me not providing proof of any kind".

Like you can say one amp sounds better to you than the other, that's fine. But don't say it does so because you can 'feel' and 'hear' 96kHz frequency or that because you can hear the difference two amps, you are also able to inexplicably hear such frequencies without demonstration. It's a non sequitur because the two concepts don't relate to one another, and also the prior probability of it being true is virtually 0% (as no one has ever demonstrated such an ability like hearing such frequencies).

Worst of all, when you have the "I hear 96kHz" sort of add-on conclusion to you argument. It makes your prior subjective one hold less credence. In the same way your friend who said he could tell the difference between 5 minute old beer vs 10 minute old beer and likes the 10 minute old beer for it's taste, but then goes on to say because of such ability he also convinced an Victoria's Secret model to have sex with him last night, and also he believes humans can breathe in outer space, and also he knows Mars is only 500 miles away from Earth.

I'm not saying you're doing exactly this. I'm just trying to demonstrate where your claim on "subjective opinions aren't allowed" would actually warrant people telling you to end the nonsense. Giving a subjective review of what you hear isn't against the rules. But whether or not you have people believe your claims, or whether they value your opinion all equally isn't something you can guarantee regardless of community.

Even in a community like this that values objectivity, you have folks who would wish for more stringent sorts of tests, or more types of tests.

There's no need for baseless blanket statements like that man... we're all here for the same reason (I hope) to get a better understanding of what it is we're doing and how we engage with audio products.
 
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amirm

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It was an interesting read. But was it skewed to suit the MQA narrative?
It was related to reference [9] on audibility of sharp filters to truncate high-bandwidth music into 44.1 kHz. Seems someone was questioning the results, staying people were hearing intermodulation distortions from speakers and not the effect of the filter.
 

Tks

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It was related to reference [9] on audibility of sharp filters to truncate high-bandwidth music into 44.1 kHz. Seems someone was questioning the results, staying people were hearing intermodulation distortions from speakers and not the effect of the filter.

Hey Amir, I was wondering just on the side, has any 3rd part audit of MQA been done by researchers to validate the functions and what they do precisely themselves? Like how 3rd party folks exist to audit the security of code even if it's fully closed source?
 
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amirm

amirm

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Hey Amir, I was wondering just on the side, has any 3rd part audit of MQA been done by researchers to validate the functions and what they do precisely themselves? Like how 3rd party folks exist to audit the security of code even if it's fully closed source?
Companies who have licensed it may have done their own audit/evaluation. Nothing has been announced or is public though. McGill University did some MQA testing but I don't remember if they got the encoder or sent files to MQA to be encoded.
 

Tks

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Companies who have licensed it may have done their own audit/evaluation. Nothing has been announced or is public though. McGill University did some MQA testing but I don't remember if they got the encoder or sent files to MQA to be encoded.

Thank you for the update. I find it hard to believe after all this time no one has been granted access to publish some results of their findings of the encoder itself for example. You would think they'd be rushing for everyone and anyone to clearly demonstrate their findings if this whole MQA ordeal had any serious implications to perceived benefits.

Again, while my understanding would require a laymen even dumb-down their findings for me, the simple examination of behavior nearly-always seems to confirm the worst skepticism people have from entities that present themselves in this sort of way.
 

Jimster480

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Wow looks very good! I really wonder what the pricing will be..... seems like they are giving benchmark a run for their money (literally).

Also there is a typo in the conclusion where you write "hyex" rather than hypex.
 

tktran303

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well... I dont think so, but I did bulk at the first statement
High-resolution recording and playback systems should accept signal components above 20 kHz and preferably reproduce above 40 kHz

On what basis? You cant hear it, and in theory at least, it has the potential to create in band IM problems.?!?!?!?!

It also seemed a totally pointless exercise to stimulate the speakers with such unrealistically high SPL ultrasonic signals that will never occur in any real recording.

The conclusion really is "nothing to see here".

Amps/sources and DACs going out to 100Khz and beyond...really??!

The industry is still trying to sell us what we don’t need, or may even harm our playback quality.

Sending my tweeters 20-80KHz signals is as dumb as sending my subwoofers 2-10Hz signals.

Yes, when I was 18 seeing subwoofers flapping in the wind and groaning under distress was fun, but really after ruining the suspensions and bottoming out the voice coils.... well I want that as much as I want more IM distortion in my tweeters.
More lucidly explained in text (and video) than any other:
https://people.xiph.org/~xiphmont/demo/neil-young.html
 
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March Audio

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Amps/sources and DACs going out to 100Khz and beyond...really??!

The industry is still trying to sell us what we don’t need, or may even harm our playback quality.

Sending my tweeters 20-80KHz signals is as dumb as sending my subwoofers 2-10Hz signals. Yes, when I was 18 seeing subwoofers flapping in the wind and groaning under distress was fun, but ruining the suspension and bottoming out my voice coils.... well I want that as much as I want more IM distortion

More lucidly explained in text (and video) than any other:
https://people.xiph.org/~xiphmont/demo/neil-young.html
Good old Monty :)!
 
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